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Insects and other arthropods

Woodlice

English
Wood louse, adult.
Photo: René Limoges
Oniscidea
  • Oniscidea
  • Oniscidea
  • Oniscidea

Tabs group

Description

Woodlice have an oval body and are between 12 and 15 mm long. They are typically grey, brown or black in colour. Their body is protected by a shell-like exoskeleton. They have seven pairs of legs.

The English-speaking world separates woodlice into two groups: sowbugs and pillbugs. Sowbugs possess two tail-like appendages at the tip of the abdomen. Pillbugs have no posterior appendages and can roll up into a tight ball when disturbed.

Life cycle

Mating is difficult to observe, but a researcher supplied the following description, which likely applies to more than one species.

The male touches the female with his antennae. If she is receptive, he climbs on her back, positions himself diagonally and transfers sperm to one of her genital openings, a process that lasts several minutes. He then changes position to pass sperm to her second genital opening, since she has two genital openings, one on either side of her body.

The female has a fluid-filled brood pouch under her thorax in which she lays her eggs and where they hatch. The young in all species are white when they emerge, and their colour develops after several days. While they look like adults, they have only six pairs of legs; they gain their seventh pair after the first moult. Juveniles moult at regular intervals until they reach sexual maturity, usually within a year.

The life cycle varies widely according to the species.

French name
Cloportes (bibittes à bois)
English name
Woodlice (sowbugs, pillbugs)
Class
Malacostraca
Order
Isopoda